Apparatus for automatically gating signals to one of a plurality of blocking oscillators



United States Patent 3,337,809 APPARATUS FOR AUTOMATICALLY GATlNGSIGNALS TO ONE OF A PLURALITY OF BLOCKING OSCILLATORS Richard O.Eastman, San Diego,

Mesa, John A. Waterbury and Wayland A. Carlson, San Diego, and Ralph H.Miller, Jr., La Mesa, Calif., assignors to the United States of Americaas represented by the Secretary of the Navy Original application June28, 1961. Ser. No. 122,056. Divided and this application June 27, 1963,Ser. No. 291,224

2 Claims. (Cl. 328--55) The invention described herein may bemanufactured and used by or for the Government of the United States ofAmerica for governmental purposes without the payment of any royaltiesthereon or therefor.

The present invention is a divisional application of copendingapplication Ser. No. 122,056 filed June 28, 1961, entitled, QuantizedPulse Modulated Non-Synchronous Clipped Speech Multi-Chaunel CodedCommunication System.

The present gating circuit is intended to be used with the subjectmatter of the aforesaid co-pending application and is necessary due tothe short interval between pulses at the input to the gating circuit,i.e., faster than the recovery time of an ordinary gating circuitcomprising, for instance, a blocking oscillator.

An object of the present invention is to provide an improved gatingcircuit.

A further object of the present invention is to provide an improvedgating circuit wherein the recovery time of the gating circuit may begreater than the interval between input pulses to the circuit.

Another object of the present invention is to provide an improved gatingcircuit wherein the time interval between input pulses to the circuitmay be less than the recovery time of the individual blocking oscillatorof the gating circuit.

Other objects and many of the attended advantages of this invention willbe readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

FIG. 1 is a block diagram of one embodiment of the gating circuit; and

FIG. 2 is a timing diagram associated with the block diagram of FIG. 1.

The embodiment set forth in FIG. 1 illustrates the gating circuitwherein an input from the video amplifier of co-pending application Ser.No. 122,05 6 is coupled in at input 10 to a diiferentiating amplifier11. The output from the differentiating amplifier 11 is coupled to agated switch 12 having a grid 13 and plates P and P In additional thereis a focusing electrode at 14 which is adapted to move an electron beambetween P and P The output of plate P is connected to a blockingoscillator 15 and the output of the blocking oscillator coupled to abuffer amplifier and delay unit 16, thence to a pulse stretcher 17 theouput of which is coupled to a pulse amplifier 18. Another output fromthe oscillator 15 is coupled directly to output 20. The output of thepulse amplifier is coupled back to the focusing electrode 14.

The output of plate P is coupled to another blocking oscillator 19, theoutput of which is connected to output terminal 20 which is a utilizeddrive to a delay line as set forth in co-pending application Ser. No.122,056.

William W. Dyer, La

Operation When the receiver unit of co-pending application Ser. No.122,056, is set for a maximum sensitivity, the video ice output from thereceiver is composed of variable signals and noise spikes of 0.5 volt.Since the remaining circuitry of the master decoder unit of theaforesaid co-peuding application generates pulses upon the reception ofany trigger, noise effects must be minimized. This is accomplished bybase clipping the noise spikes, as shown in FIG. 2. The gated switch 12is biased below cut-off by the setting of a trigger level control, notshown. The amount of clipping is then determined by how far belowcut-off the gated switch 12 is biased and by the magnitude of the signalpresented to its grid 13. By adjusting various controls, an optimumcondition can be established between desired signals and noise spikesand after testing the aforesaid controls by jamming tests, it waspossible to obtain adequate operation of the system of co-pendingapplication Ser. No. 122,056 when the desired signals exceeded noise orpulse jamming signals by only 25%.

The delay line 74 of co-pending application Ser. No. 122,056 is a majorcomponent of the master decoder unit and the circuity of the masterdecoding unit serves primarily to provide a high-amplitude low-impedancedrive-for this delay line. In ordinary operation a single blockingoscillator could provide this driving function, however, due to thedecoding of the plus or minus 0.3 microsecond modulation from the inputpulse trains, it is necessary to generate pulses 0.7 microsecond wideand as close together as 0.85 microsecond. The recovery characteristicsof blocking oscillators preclude the use of a single unit for such rapidoperation. Hence, it is necessary to provide two blocking oscillatorswhich operate alternately when the fastest triggering becomes necessary.Therefore, a master blocking oscillator 15 is provided and a secondblocking oscillator 19 is switched in only as needed. The timing of thiscircuitry is shown diagrammatically in FIG. 2.

In the operation of the master decoding unit of the aforesaid co-pendingapplication Ser. No. 122,056 a pulse from the video amplifier is coupledin at 10 at times T and T and is difierentiated in the differentiatingamplifier 11 and base clipped. This pulse is then coupled to the gridand to plate P which triggers blocking oscillator 15 thereby generatinga 0.7-microsecond pulse. One output of blocking oscillator 15 is coupledto the output terminal 20 and the other output is applied to the gatingcircuit. The gating circuit comprises the buffer, amplifier and delayunit 16, pulse stretcher 17 and pulse amplifier 18. The gating circuitsdelay the pulse by 0.75 microsecond and then stretch the pulse to aneffective width of 1.4 microseconds. The stretched pulse is thenamplified in the pulse amplifier 18 and returned to the focusingelectrode 14 of the gated switch 12, causing the beam to switch to Pduring the gate intervals of 1.4 microseconds. This gate interval coversthe modulation region of the succeeding adjacent channel, yet is narrowenough to insure recovery between alternate regions.

If an input pulse occurs during the 1.4 microsecond gating interval, ittriggers blocking oscillator 19 which also generates a 0.7 microsecondpulse. The output of either block oscillator can drive the delay line ofcopending application Ser. No. 122,056 which is adapted to be coupled tooutput terminal 20.

The foregoing description of the present invention illustrates a gatingcircuit which is adapted to handle extremely high-speed input pulseswherein the time interval between pulses is less than the recovery timeof the blocking oscillators used to generate the output pulses. Inaddition, the gating circuit is made up of conventional components whichare readily obtainable and easily maintained.

Obviously, many modifications and variations of the present inventionare possible in the light of the above gated switch means comprising aninput means, first and second output elements and a focusing element soconstructed and arranged that a conducting path exists selectivelybetween said input element and said first and second output elementswhen said gated switch is activated;

blocking oscillator means connected to one of said first and secondoutput elements for generating output pulses when triggered by an inputpulse thereto;

delay means operatively receiving output pulses from said first blockingoscillator means for delaying the output pulses;

pulse stretcher means operatively receiving the output of said delaymean's'for increasing the time width of said pulses;

said focusing element operatively receiving said stretched and delayedpulses from said pulse stretcher means and switching said beam betweensaid input element and the other of said first and second outputelements at a time determined by said stretched and delayed pulse width;

second blocking oscillator means operatively coupled to the other ,ofsaid first and second output elements for generating output pulses whentriggered by an input pulse; and

output terminal means operatively receiving output pulses from saidfirst and second blocking oscillators. 2. A ring around gating circuitcomprising;

input means for receiving time modulated pulses at a rapid rate;

gated switch means including a first input element, first and secondoutput elements and a focusing means;

first blocking oscillator means operatively coupled to one of said firstand second output elements and receiving pulses therefrom when pulsesare coupled from said input element to said first output element;

delay means operatively receiving the output of said first blockingoscillator means for delaying said pulses a predetermined amount;

pulse stretching means operatively coupled to said delay means forincreasing the pulse width of said pulses;

said focusing means operatively receiving said stretched and delayedpulses and causing the pulse path existing between said input elementand said one of said first and second output element to be switched tothe other of said first and second output element; and

second blocking oscillator means operatively coupled to said other ofsaid first and second output elements for generating pulses and outputterminal means operatively coupled to said first and second blockingoscillators for receiving output pulses therefrom.

References Cited UNITED STATES PATENTS 2,647,172 7/1953 Ieanlin 33 1-49ARTHUR GAUSS, Primaly Examiner.

K. CLAFFY, Examiner.

S. D. MILLER, Assistant Examiner.

1. A GATING CIRCUIT COMPRISING; INPUT MEANS FOR COUPLING PULSES THERETOAT A HIGH RATE; GATED SWITCH MEANS COMPRISING AN INPUT MEANS, FIRST ANDSECOND OUTPUT ELEMENTS AND FOCUSING ELEMENT SO CONSTRUCTED AND ARRANGEDTHAT A CONDUCTING PATH EXISTS SELECTIVELY BETWEEN SAID INPUT ELEMENT ANDSAID FIRST AND SECOND OUTPUT ELEMENTS WHEN SAID GATED SWITCH ISACTIVATED; BLOCKING OSCILLATOR MEANS CONNECTED TO ONE OF SAID FIRST ANDSECOND OUTPUT ELEMENTS FOR GENERATING OUTPUT PULSES WHEN TRIGGERED BY ANINPUT PULSE THERETO; DELAY MEANS OPERATIVELY RECEIVING OUTPUT PULSESFROM SAID FIRST BLOCKING OSCILLATOR MEANS FOR DELAYING THE OUTPUTPULSES; PULSE STRETCHER MEANS OPERATIVELY RECEIVING THE OUTPUT OF SAIDDELAY MEANS FOR INCREASING THE TIME WIDTH OF SAID PULSES; SAID FOCUSINGELEMENT OPERATIVELY RECEIVING SAID STRETCHED AND DELAYED PULSES FROMSAID PULSE STRETCHER MEANS AND SWITCHING SAID BEAM BETWEEN SAID INPUTELEMENT AND THE OTHER OF SAID FIRST AND SECOND OUTPUT ELEMENTS AT A TIMEDETERMINED BY SAID STRETCHED AND DELAYED PULSE WIDTH; SECOND BLOCKINGOSCILLATOR MEANS OPERATIVELY COUPLED TO THE OTHER OF SAID FIRST ANDSECOND OUTPUT ELEMENTS FOR GENERATING OUTPUT PULSES WHEN TRIGGERED BY ANINPUT PULSE; AND OUTPUT TERMINAL MEANS OPERATIVELY RECEIVING OUTPUTPULSES FROM SAID FIRST AND SECOND BLOCKING OSCILLATORS.